I am slightly on the fence now between two different motherboards/cpu itx systems to do my sega genesis mod. I want it to be able to play up to 1080p movies (which i know either can) and as well run emulator games with no problems (which i know both can). What comes down to it is i dont know if the cost difference is worth going from a single core with ht atom to a dual core with ht atom (may attempt to see what ppd a n330 could kick out). Both already come with the dc power adapter which is why i'm looking at them.

Next Level Hardware.com: Intel QX9650 Quad Core Review
Only review I could find comparing the 2, don't know if it will help any. Personally, I'd just spend the bit extra and go with the 330. I'd imagine it would give a bit of overhead in case you threw something else at it while running the high def stuff. My 2 pents.

I have no plans in added a gpu, as the 9400M should be able to handle everything thrown at it. Its just the justify the 40-50$ price difference for an extra physical core and therefore 2 extra logical cores